There are 6,125 state legislative districts, in 46 states, with a seat up for election on November 2, 2010. We took a look at each of the 46 states to see how many state legislative incumbents who chose to run for re-election in 2010 faced a primary challenger.

Our main findings:

The incumbent chose to run for re-election in 4,985 (81.4%) of the 6,125 districts holding state legislative elections in 2010.

In 3,861 (77.31%) of those 4,985 districts, the incumbent faced no challenger in the primary.

Comparing states:

North Dakota, Colorado, Connecticut, Maine and Minnesota have the fewest incumbents facing primary opposition -- in other words, these five states had the least amount of competitiveness at the primary level.

The five states with the most competitive primaries in terms of incumbents facing primary challengers are New Hampshire, Maryland, Nebraska, West Virginia and Arizona.

States compared by primary competition

The state that is least competitive as defined by the percentage of its seats where the incumbent did not have a primary challenger in 2010 is defined as #46, while the state that is most competitive as defined by the percentage of its seats where the incumbent did have a primary challenger is defined as #1; that is, 1 = "most competitive", 46 = "least competitive".